Preparing the F104 for foam tire racing is not hard, but there are some subtle tweaks which will really help the potential of the car.
Any version of the F104 is suitable for foam tire racing. Although the F104 Pro does come with the graphite chassis, the FRP chassis is just about as stiff, with a slight weight penalty. The bodies are also not a game changing matter. The F60 Ferrari does offer a wider front wing, which helps to keep your wheels free in an accident. That is probably the biggest advantage, besides a bit more weight over the nose. The upcoming McLaren body should be similar.
The tires are a different matter however. The kit foams from the F104 are very good on carpet, and probably should be your #1 choice for that surface. They are similar to the "gray/white/yellow" type of foam, which has less rubber content. The kit tires will help the car have a fairly mellow feel. The "B" tires are like the "purple" or "pink" family of tires which have a lot of rubber content. They are great for asphalt, but may cause the car to be erratic on carpet. You can mix the two types of tires, but I have found that this is not ideal for carpet.
The double sided tape that comes with the tires is ok, but I have found that CA glue or contact cement is much better. CA is good if you need to mount tires NOW, but otherwise it is a hassle. A lot of care must be taken to make sure the CA gets to the center of the tire to adhere it, and you tend to glue yourself and the tire to everything.
Contact cement is easier to deal with, but takes a bit longer:
*Liberally coat the wheel and inside of tire with cement. Let stand until dry - usually less than an hour, but longer is better
*Dunk tire and wheel into lacquer thinner.
*Set wheels face down on table. **MAKE SURE IT IS A "WORK" SURFACE**
*Slide tire onto wheel. You can use the table to help ensure the tire is even with the wheel face.
*Let stand overnight to dry.
3M Super Weatherstrip Adhesive # 8001 (yellow) works well and can be had at auto parts stores.
You'll want to true the tires as well. Start the rears in the 56-57mm range. I have found that the silver can motors tend to like a larger rear tire. I'm not sure if it is the way the tire rolls or a gearing advantage, but there is a difference. The fronts can be started in the same range, or even a bit smaller since the 104 has ride height control at the front. A smaller front tire will be more important if the track is high bite, as it will make the car more consistent. Lower bite or asphalt tracks will generally like a bigger tire.
Doping the tires, no matter what additive you use, is really important. I always dope the entire rear, and 2/3 to the whole front when using the kit tire on carpet. Obviously, the more you coat the front, the more steering. The B tires are more aggressive, and you're most likely not going to need to use anywhere near as much sauce on the fronts.
As far as asphalt racing, most places I have been to I have used Paragon FXII (white can) on foams, and them re coated that with sunscreen. I use a high SPF white cream type sunscreen, any generic brand works. The Paragon should soak in for around 10 minutes or until it's all the way into the tire, then re coat with a generous amount of sunscreen. Wipe the heat before your race and you are set. Paragon Ground FX (black can) works well when it is a bit colder out and Trinity Red Dot works at some tracks as well.
On the front end, there are several important adjustments. First off the, RC F104 Alum Upper Susension Mount, #54202 is a worthwhile option part because the ability to set camber in .5* increments is very helpful. Start with 1*, and you can move up if you feel you want the car to be more aggressive. Note that you will start to cone the tire or get excess wear as you increase camber. Along with this, the upper arm angle sets the dynamic caster effect on the front end. What this means is the caster angle changes as the suspension moves. Increasing the height of the rearward ball (chassis), or lowering the forward ball (camber mount) will increase the arm's angle. This causes the car to pick up more mid corner grip in the front. Your car will have less tendency to push out mid corner. You can usually add about 1mm to the rear ball, and Tamiya makes a 1mm lower height ballstud you can use on the camber mount to also increase this effect. Also not that the upper arms can be tight on the ballstuds, and you may need to take a pliers and slightly crimp the arm where it pops over the ballstud to free this up.
Normally, the black front spring is all you will ever need to run with foam tires. For carpet, I will use 60,000 wt diff oil on the king pin, possibly going up to 100,000 wt if conditions warrant it. Coat the kingpin where the spring rides, and where it passes through the suspension balls. Remember, keep it neat, not too heavy on application.
Hey Rob K.
Thank you, For taking the time out of your busy schedule to share with us this valuable imformation. We appreciate you!
-TMarshall